1. Field of Invention
This invention relates to imaging devices. Specifically, the present invention relates to systems and methods for optically butting focal plane arrays.
2. Description of the Related Art
Imaging systems are used in a variety of demanding applications ranging from infrared missile tracking systems to commercial video cameras to airborne and space-based remote sensing systems. Such imaging systems often require very reliable and precise components such as focal plane arrays to handle very large images.
Focal plane arrays of energy detectors are used to convert incoming images into electronic form for further image processing, enhancement, information extraction, or display. Typically a focal plane array detects an image in the form of incoming electromagnetic energy such as light or infrared energy and converts the image into electronic signals for further signal processing.
Reliable precise, and cost effective focal plane arrays that can handle very large images are difficult to obtain. Large, high quality semiconductor wafers required for large focal plane arrays are often rare and expensive. Typically several focal plane arrays must be manufactured before obtaining an array of sufficient quality for use in present imaging systems. Such large focal plane arrays are very expensive and often impractical.
To avoid the problems and low yields inherent in large focal plane arrays, a method for optically butting two smaller arrays was developed. Small, high-quality focal plane arrays are less expensive and easier to manufacture than one large array of equivalent surface area. The method utilizes a prism that splits an incoming image into two smaller images. Each smaller image is sent to a different focal plane array. The two smaller images are then combined electronically. However, unavoidable manufacturing imperfections at the apex of the prism typically result in a "dead pixel" region at the boundary between the two focal plane array images in which no image information is obtained. As the display resolution of imaging systems increases, the presence of a dead pixel region corresponding to a region containing no image information in the center of a reconstructed image becomes more problematic. Physically butting focal plane arrays results in similar imperfections.
Hence, a need exists in the art for a system for butting focal plane arrays of detectors that eliminates the dead pixel region between focal plane array images.